General visible light communication is performed through a process in which a transmitter outputs a visible light by using a light source such as a Light Emitting Diode (LED) or a Laser Diode (LD) and a receiver processes the visible light by using a Photo Detector (PD). As a light emission efficiency of the LED has been improved and a cost of the LED has been reduced, the LED has been generalized in a typical lighting market including a fluorescent light and an incandescent light as well as a special lighting market including a portable device, a display, a vehicle, a traffic light, and a billboard.
Particularly, a market including a large size billboard also has been continuously grown. A market of a billboard using a large size LCD screen has been continuously grown in the market of the large size billboard. The billboard is called various names such as a Digital Information Display (DID), a Digital Signage (DS), and a Large Format Display (LFD). For example, a DID device uses a technology of innovating a paradigm of information transmission through bidirectional communication between a user and a supplier by combining a function executed by a notice using a conventional paper medium and a unidirectional advertisement through broadcasting and a function executed by a display and an Information Technology (IT), which is spotlighted as a technology of having a cost reduction effect in a long-term point of view in comparison with a conventional transmission medium. A recent DID technology extends its business area to outdoor advertisement and 3 Dimensional (3D) fields, and accordingly, general people easily encounter advertisement media to which a DID solution is applied.
Various information display devices having a display unit in addition to the DID device adopt the LED for a BackLight Unit (BLU) for lighting. Since the LED may be used as a light source for visible light communication, research on information display devices having more convenient and various functions using the backlight unit adopting the LED is required.